Risa

I sometimes think about this. Imagine you were an "immortal" being or mind in a powerful starship that could interfere with Earth. Like you could prevent the plague killing millions, but if you do we humans might not learn sanitation - or they need to learn later. Or do you prevent climate change because you know it will kill us all - but then humanity won't learn and "evolve". So when humanity does finally become interstellar and spreads over the galaxy, terraforming every planet and harvesting every resources, bulldozing everything and endlessly and exponentially grow - is it your fault?

As soon as you interfere you take on responsibility and guilt for every genocide or ecocide this civilization is going to commit in the future.

Outside completely cosmological threats it becomes quite iffy. Even something like a planet killer meteor could be argued that if the species knew it could happen but didn't put effort into preventing it, then that means they don't value survival of intelligent civilizations enough. They don't value theirs, why would they value other civilizations they encounter?

In reality Star Trek colonizing all these planets would eliminate future intelligent civilizations too. Imagine some star trek people would have stepped on Earth a hundred million years ago and found no signs of intelligent live, terraformed it. Or even just introducing countless microorganisms on your shoe. You wouldn't be able to read this silly comment :D It would be a kind of temporally displaced genocide. Of course NASA is already thinking about this and no colonization would make for rather boring drama, but a modern "hard sci-fi" would have to have artificial space habitats (orbitals / halos) as the main living spaces and leave any potentially live giving planets alone.

Then another argument would be about diversity. For an immortal being, planets could be seen as bio computers creating incredibly complexity and irreplaceable wealth of information. A new way to exist or how not to exist. As soon as you interfere you taint that and have removed some of distinctiveness of their culture with your own culture.